The present invention relates to a sample separation system.
In liquid chromatography, a fluidic sample and an eluent (liquid mobile phase) may be pumped through conduits and a column in which separation of sample components takes place. The column may comprise a material which is capable of separating different components of the fluidic analyte. Such a packing material, so-called beads which may comprise silica gel, may be filled into a column tube which may be connected to other elements (like a sampler, a detector) by conduits.
The composition of the mobile phase can be adjusted by composing the mobile phase from different fluidic components with variable contributions, so called gradient mode. HPLC systems often are operated in such a gradient mode, wherein for instance for reversed phase chromatography the organic content is ramped over time, or for ion exchange chromatography the salt content is ramped over time. Especially in peptide or protein analysis most applications are based on water/acetonitrile gradients. An analytical protocol for running a defined analytical process is called the “method”. In the analytical protocol—or method—for a gradient separation, the gradient is usually defined as a composition change program over time, while the flow rate is kept constant. The so-called retention time is a time required for transport of a certain component of a fluidic sample to be separated throughout a separation column during a gradient run.
Alternatives to the concept of retention times are known such as the concept of retention volumes. Particularly, WO 2009/062538 A1 discloses in a high performance liquid chromatography system, wherein a mobile phase is driven through a stationary phase for separating components of a fluidic sample comprised in the mobile phase, a flow rate of the mobile phase may not be constant and may depend on a variation in a control value in the system. WO 2009/062538 A1 comprises determining (for instance by an adequate analysis unit, which considers predicted, measured or elsewise derived flow information) a value of a retention volume representing such volume of the mobile phase required to elute a respective compound of the fluidic sample at least through the separating device. The mobile phase drive is then operated (for instance by an adequate control unit) based on the determined value of the volume delivered into the system. This makes use of the concept of retention volumes, rather than retention times.
Two-dimensional separation of a fluidic sample denotes a separation technique in which a first separation procedure in a first separation unit is performed to separate a fluidic sample into a plurality of fractions, and in which a subsequent second separation procedure in a second separation unit is performed to further separate at least one of the plurality of fractions into sub-fractions. Two-dimensional liquid chromatography (2D LC) may combine two liquid chromatography separation techniques and plot the time dependency of detection events along two orthogonal time axes.